Pemphigus Vulgaris Mimicking Seborrheic Dermatitis: A Case Report.

This case discusses a 55-year-old patient who was evaluated at a dermatology outpatient clinic for a chronic, pruritic, and painful hyperkeratotic plaque located on her scalp vertex. Given the size of the plaque and its thick, yellow scales, an initial clinical diagnosis of seborrheic dermatitis was favored. However, after weeks of unsuccessful treatment with ketoconazole shampoo, topical fluocinolone 0.01% oil, mupirocin ointment, and oral doxycycline, it became apparent that deeper investigation and reconsideration of the original diagnosis were warranted. A punch biopsy and direct immunofluorescence of the lesion were performed, and the results revealed a final diagnosis of pemphigus vulgaris (PV). This case highlights the complexity of dermatology and the challenges in achieving an accurate diagnosis based solely on clinical features, mainly when diseases exhibit overlapping characteristics or are present in less familiar ways. Distinguishing between conditions with similar features can be particularly difficult and becomes even more crucial when one condition is benign, and another is potentially fatal. Therefore, we recommend further investigating when a skin condition does not resolve or fails to respond to multiple treatment attempts.